Make sure you do not use keep alive on the server or zoiper could get killed. Other than that it should work reliably. It could fail for maximum 10 minutes if there was no network for a while.

In such case, zoiper would lose the TCP connection, have limited time to try to reconnect before being forced to sleep by ios and since there is no active TCP socket, not be notified about a new network change.

Please also check the registration expiry on the server, it should be a minimum of a minimum of 10 minutes. If that doesn't work, please send us an email on support@zoiper.com with the exact model of phone, version of ios and if you connect on wifi or 3g/4g so that we can test the scenario in the lab.